treewide: internally avoid deprecated machine file uses of "pkgconfig"

We support this in a machine file:

```
[binaries]
pkgconfig = 'pkg-config'
pkg-config = 'pkg-config'
```

and you can use either one, because internally we look up both. If you
only set *one* of them, this plays awkwardly with setting $PKG_CONFIG,
since we don't know which one you set in the machine file and the
*other* one will be initialized from the environment instead.

In commit 22df45a31981874310a78dde0df59a6a7c5ebb29 we changed program
lookup of config-tool style dependencies to use the regular tool names
and only fall back on the strange internal names. This affected the
pkg-config class too.

The result is that instead of preferring `pkgconfig =` followed by
$PKG_CONFIG followed by `pkg-config =`, we inverted the lookup order.
This is a good idea anyway, because now it behaves consistently with
`find_program('pkg-config')`.

Unfortunately, we documented the wrong name in a bunch of places, and
also used the wrong name in various testsuite bits, which meant that if
you set $PKG_CONFIG and then ran the testsuite, it would fail.

Correct these references, because they are buggy.

One test case expected to find_program() a native copy for convenience
of testing against natively installed glib. Force it to resolve a native
copy.

1 files changed, 2 insertions, 2 deletions

diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 12eafd5..4327d99 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -2722,7 +2722,7 @@ class AllPlatformTests(BasePlatformTests):
         with tempfile.NamedTemporaryFile(mode='w', delete=False, encoding='utf-8') as crossfile:
             crossfile.write(textwrap.dedent(
                 '''[binaries]
-                pkgconfig = '{}'
+                pkg-config = '{}'
 
                 [properties]
 
@@ -2749,7 +2749,7 @@ class AllPlatformTests(BasePlatformTests):
         with tempfile.NamedTemporaryFile(mode='w', delete=False, encoding='utf-8') as crossfile:
             crossfile.write(textwrap.dedent(
                 '''[binaries]
-                pkgconfig = 'pkg-config'
+                pkg-config = 'pkg-config'
 
                 [properties]
                 pkg_config_libdir = ['{}']